Name: how allosteric control changes enzymes
Uploaded: 2020-11-23T11:47:34.000Z
Duration: 1 min 8 s
Channel: JoVE

K12 Standards

Tennessee Academic Standards

High School

Biology

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

BIO1.LS1.3

Allosteric Regulation

Die allosterische Regulation bezieht sich auf die Kontrolle eines Enzyms durch eine andere Stelle als die aktive Stelle des Enzyms.
 Wenn ein Molekül sich an einen solchen Ort bindet, der als allosterische Stelle bezeichnet wird.
 Die Bindung kann eine Konformationsänderung oder eine Formänderung im Enzym induzieren.
 Eine solche Wirkung kann eine Erhöhung der Affinität der aktiven Zentren des Enzyms zu seinen Substraten verursachen, wodurch die Aktivität des Enzyms erhöht wird.
 Ein Prozess, der als allosterische Aktivierung bekannt ist.
 In einem Reaktionsgeschwindigkeits-Substratkonzentrations- Diagramm kann die allosterische Aktivierung als positive S-förmige Kurve dargestellt werden.
 Wo es eine Verzögerungszeit gibt, bis das Enzym aktiviert wird.
 Dann kann aufgrund des plötzlichen Anstiegs der aktiven Stellen eine hohe Substratkonzentration binden und die Reaktion schnell beschleunigen.
 Wenn sich andererseits der Effektor an das Enzym bindet und eine Konformationsänderung verursacht, die die Affinität der Substratbindung verringert, wird der Prozess als allosterische Hemmung bezeichnet.
 In diesem Fall gibt es eine Abnahme der Enzymfunktion und einen Abfall der Geschwindigkeit der chemischen Reaktion aus dem aktivierten Zustand.

<ol><li>Cornish-Bowden, A. Verständnis allosterischer und kooperativer Wechselwirkungen in Enzymen. Das FEBS Journal. 281 (2), 621-6332 (2014).</li><li>Tsai, C.-J., Nussinov, R. Aufkommender allosterischer Mechanismus der EGFR-Aktivierung in physiologischen und pathologischen Kontexten. Biophysikalische Zeitschrift. 117 (1), 5-13 (2019).</li></ol>

allosterische regulation

Die allosterische Regulation von Enzymen tritt auf, wenn die Bindung eines Moleküls an einer anderen Stelle als dem aktiven Zentrum eine Veränderung der enzymatischen Aktivität bewirkt. Diese Art der Regulierung kann entweder positiv oder negativ sein. Die Enzymaktivität wird entweder erhöht oder vermindert. Die meisten Enzyme, die eine Allosterie aufweisen, sind Stoffwechselenzyme. Sie nehmen am Abbau oder an der Synthese spezifischer Zellmoleküle teil.
 
 Bei der allosterischen Hemmung bewirkt die Molekülbindung an der allosterischen Stelle eine Strukturveränderung, wodurch die Affinität des Enzyms zum Substrat verringert wird. Häufig ist der allosterische Inhibitor ein Produkt des Enzyms oder des Signalweges des Enzyms, wodurch die enzymatischen Produkte ihre eigene Produktion einschränken können. Dies ist eine Art der Rückkopplungshemmung, bei der eine Überproduktion von Stoffen verhindert wird. Ein klassisches Beispiel ist Isoleucin, da es ein allosterischer Inhibitor eines Enzyms ist, welches wichtig für seine Synthese ist.
 
 Im Gegensatz dazu bewirkt ein allosterischer Aktivator eine Veränderung der Konformation des Substrats. Diese erhöht die Affinität des Enzyms zum Substrat. Die allosterische Aktivierung erhöht dramatisch die Reaktionsgeschwindigkeit, was durch eine S-förmige Geschwindigkeit-Substrat-Kurve dargestellt wird. Als Beispiel verursacht die Bindung des extrazellulären Liganden an den transmembranen EGF-Rezeptor eine Konformationsänderung, die zur Aktivierung der intrazellulären Kinaseaktivität führt. Wenn ein Enzym aus mehreren Untereinheiten zusammengesetzt ist, kann die Bindung eines allosterischen Aktivators an eine einzige Untereinheit eine Erhöhung der Affinität und eine Formveränderung für alle verbundenen Untereinheiten hervorrufen.

Allosterische Regulation

Die allosterische Regulation von Enzymen tritt auf, wenn die Bindung eines Effektormoleküls an eine Stelle, die sich von der aktiven Stelle unterscheidet, eine Veränderung der ...

Education

Lehre

JoVE Core

Molecular Biology

Molekularbiologie

Unit 1

Einheit 1

Protein Function

Proteinfunktion

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

how allosteric control changes enzymes

Allosteric control changes how enzymes work by using a site other than the active site. A small molecule binds to this separate allosteric site and changes the enzyme’s shape. That shape change can alter how well the enzyme binds its substrate and how fast the reaction runs.

Many enzymes use this kind of regulation to turn activity up or down when the cell needs it. In some cases, the allosteric molecule acts as an activator and improves enzyme function. In other cases, it acts as an inhibitor and reduces enzyme function. This control helps cells manage reactions without changing the enzyme’s basic structure.

Allosteric regulation is an important way proteins respond to signals in the cell. It shows how a binding event at one site can affect activity at another site. For high school biology, it is a key example of how protein shape and function are linked.

How Allosteric Control Changes Enzymes

ligand binding sites

How Ligands Attach to Proteins

Ligands attach to proteins at specific binding sites on the protein surface. These sites let proteins interact with other molecules or ions and help them carry out important cell functions. Although many possible ligands may be nearby, only a matching ligand can bind to a given protein. A ligand-binding site has a shape and chemical pattern that fit its ligand. This fit comes from the protein’s amino acid chain, which gives the site its structure and reactivity. The ligand stays in place...

protein-protein interfaces

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conserved binding sites

Predicting Protein Ligand-Binding Pockets

Protein ligand-binding pockets help explain how proteins work. A ligand is a small molecule that binds to a specific spot on a protein. These sites are often conserved in related proteins because they are important for function. When the exact site on a protein surface is not known, it can be predicted. One approach is the energetic method. It examines how amino acid residues interact with the ligand and looks for positions where the binding energy is lowest. Those low-energy regions are...

the equilibrium binding constant and binding strength

the-equilibrium-binding-constant-and-binding-strength

Measuring Protein-Ligand Binding Strength

Protein-ligand binding strength can be measured with the equilibrium binding constant, Kb. This value describes how strongly a protein binds a ligand when the reaction has reached equilibrium. In a bound complex, the protein and ligand are joined as PL, while P and L are the unbound forms. Kb can be determined in two main ways. One approach uses equilibrium concentrations. The other uses reaction kinetics, which are the rates of binding and unbinding. Kb can also be related to the binding rate...

cofactors and coenzymes

Protein Helpers: Cofactors and Coenzymes

Cofactors and coenzymes help enzymes work. Many enzymes need these helper molecules to carry out chemical reactions. Without them, the enzyme may not function properly. A cofactor is a helper molecule that can be either an inorganic ion or an organic molecule. Coenzymes are organic cofactors. They often move between enzymes and help transfer chemical groups or electrons during a reaction. Some cofactors are vitamins or come from vitamins. These molecules are important because they support...

allosteric regulation

Allosteric control changes how enzymes work by using a site other than the active site. A small molecule binds to this separate allosteric site and changes the enzyme’s shape. That shape change can alter how well the enzyme binds its substrate and how fast the reaction runs. Many enzymes use this kind of regulation to turn activity up or down when the cell needs it. In some cases, the allosteric molecule acts as an activator and improves enzyme function. In other cases, it acts as an inhibitor...

ligand binding and linkage

Allosteric Proteins: Positive and Negative Effects

Allosteric proteins have more than one ligand binding site. A ligand is a molecule that binds to a protein. When a ligand binds at one site, it can affect binding at the other sites. These sites are called coupled or linked because they influence one another. In enzymes, the site that binds the substrate is the active site. The other site is the regulatory site. When a ligand binds to the regulatory site, it can change the protein’s shape. This conformational change can then alter how the...

cooperative allosteric transitions

Allosteric Switching in Multimeric Proteins

Allosteric switching in multimeric proteins helps explain how ligand binding at one site can change the behavior of the whole protein. In these proteins, each subunit has its own ligand-binding site. When a ligand binds to one subunit, it can cause a shape change that affects the other subunits and their binding sites. This change in shape comes from the protein’s structure, which includes both flexible and stable segments. A molecule that causes the shift is called a modulator. Because the...

phosphorylation

Phosphorylation in Cell Signaling

Phosphorylation is a key step in cell signaling. It changes how a molecule behaves by adding a phosphate group. In many cells, this modification helps control activity, shape, and interactions with other molecules. Phosphorylation is carried out by enzymes called kinases. These enzymes transfer a phosphate group to a target molecule. A phosphatase can remove that phosphate group and reverse the change. Together, kinases and phosphatases help cells turn signals on and off in a controlled way. <br...

protein kinases and phosphatases

Phosphorylation Switches in Protein Control

Protein control often depends on chemical changes that alter a protein’s charge, shape, and conformation. These changes can include phosphorylation, acetylation, glycosylation, nitrosylation, ubiquitination, lipidation, methylation, and proteolysis. In cells, these modifications are usually driven by enzymes. Phosphorylation is one of the most important protein modifications. It adds a phosphate group to a protein and often changes how that protein works. A family of enzymes called kinases...

gtpases and their regulation

GTPase Signaling Switches in Cells

GTPases are cell proteins that act as signaling switches. They help control cell signaling, vesicle transport, cell shape, and cell movement. When these proteins change or stop working properly, disease can result. There are about 40,000 known G-proteins. They are usually grouped into two main types. Small G-proteins have one domain, while large G-proteins have multiple domains. Large G-proteins are also called heterotrimeric G-proteins. They have three subunits: alpha, beta, and gamma. The...

covalently linked protein regulators

How Protein Tags Change Cell Signaling

Proteins can be changed after they are made by adding small chemical tags or small proteins. These post-translational modifications help control protein function and stability when the cell environment changes. Common covalent regulators include methyl, acetyl, and phosphate groups, as well as small proteins such as ubiquitin. About 200 types of covalent regulators have been identified. These tags attach to specific amino acids in a protein. Phosphate groups can attach only to serine,...

protein complexes with interchangeable parts

protein-complexes-with-interchangeable-parts

SCF Ubiquitin Ligase and F-Box Variants

The SCF ubiquitin ligase is a protein complex that uses an F-box protein to help choose which target proteins get marked for destruction. This complex is made of five separate proteins, and each one has a different job. Together, they attach ubiquitin to target proteins so the cell can send those proteins to be degraded. The F-box protein is the part that binds the substrate, or target protein. That binding step lets the ubiquitin-conjugating enzyme reach the target and attach ubiquitin. In...

mechanical protein functions

Protein Force: Cell Movement and Support

Proteins can create and respond to mechanical force in cells. Some proteins generate force, while others are pulled or stretched by it. Proteins such as keratin provide structural support and are subjected to mechanical force. Proteins such as ion pumps help move molecules across cell membranes and can generate mechanical force. Cell movement and muscle contraction depend on turning chemical energy into motion. This often happens through conformational change, which is a shift in a protein’s...

structural protein function

Collagen and the Cell Skeleton

Structural proteins give cells and tissues shape, support, and strength. They help build bones, cartilage, hair, and muscles. Important examples include collagen, actin, myosin, and keratin. Collagen is the most abundant protein in mammals. It is found throughout the body. In skin, ligaments, and tendons, collagen adds tensile strength and elasticity. In bones and teeth, it helps form hard, load-bearing tissue through mineralization. Collagen also does more than provide support. It can...

protein networks

Mapping Protein Interactions

Mapping protein interactions shows how proteins work together in a cell. Many proteins must connect with other proteins to carry out their jobs and keep an organism healthy. These connections can be shown as protein-protein interaction networks, also called protein maps. In these maps, proteins are shown as nodes, or circles. Lines called edges connect two proteins that interact. The network can include stable interactions, such as those in protein complexes, and transient interactions that...

allosteric proteins-atcase

ATCase Feedback Inhibition in Pyrimidine Synthesis

ATCase is a key enzyme in pyrimidine synthesis. It is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to form N-carbamoyl-L-aspartate. This reaction starts the pathway that makes pyrimidines. ATCase is regulated by feedback inhibition. The end products UTP and CTP bind to the enzyme and reduce its activity when pyrimidine levels are high compared with purines in the cell. This binding at one site affects the linked catalytic site, which helps keep...

key terms and concepts

Learn how allosteric control changes enzyme activity through binding at a separate site, and how activators and inhibitors help cells regulate reactions.

How Allosteric Control Changes Enzymes | JoVE K12

molecular biology

JoVE Core Molecular Biology veranschaulicht die molekularen Prozesse der Zelle in prägnanten animierten Video-Lektionen. In Videos von Wissenschaftlern in Aktion wird die Anwendung dieser Konzepte zusätzlich durch reale Experimente in modernen Laboren demonstriert.

Arizona Science Standards

Life Science

HS+B.L1

HS+B.L1U1.5

myJoVE Corporation

Characteristics of Life

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Compare and contrast existing models, identify patterns, and use structural and functional evidence to analyze the characteristics of life. Engage in argument about the designation of viruses as non-living based on these characteristics.
EXPLANATION: Students begin to develop patterns of living and non-living organisms in kindergarten and build on detailed characteristics of different classifications of living organisms throughout elementary and middle school. Biology 1 discussions introduce viral particles and viral cycles, building on student understanding of living organisms to engage in an argument regarding the classification of a viral particle as either living or non-living.

BIO1.LS1.1

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Evaluate comparative models of various cell types with a focus on organic molecules that make up cellular structures.
EXPLANATION: Students explicitly discuss the structure and function of major cellular organelles in seventh grade. Building on this understanding, Biology I students should shift their focus to the different types of cells found in organisms and how the role of each cell type relates to its composition and the prevalence of different organelles within that cell. An example might include the absence (or enucleation) of the nucleus in red blood cells in mammals providing for increased levels of oxygen transport in organisms or the lack of centrioles in most neurons. Varying cell types can include both prokaryotic and eukaryotic cell types.

BIO1.LS1.2

Nucleic Acids

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The Central Dogma

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DNA Packaging

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Organization of Genes

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Karyotyping

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Replication in Prokaryotes

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Replication in Eukaryotes

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Mutations

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Transcription

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Transcription is the process of synthesizing RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene ...

Translation

Lesson: Translation
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RNA Structure

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pre-mRNA Processing

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Types of RNA

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MicroRNAs

siRNA - Small Interfering RNAs

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piRNA - Piwi-interacting RNAs

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CRISPR and crRNAs

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lncRNA - Long Non-coding RNAs

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Protein Folding

Protein Families

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conservation-of-protein-domains-over-different-proteins

Conservation of Protein Domains Over Different Proteins

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Globular and Fibrous Proteins

Many proteins can be classified into two distinct subtypes - globular or fibrous. These two types differ in their shapes and solubilities.
Globular ...

Intrinsically Disordered Proteins

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Protein Complex Assembly

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Conjugated Proteins

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Allosteric Proteins-ATCase

Binding sites linkages can regulate a protein&#39;s function.&#160; For example, enzyme activity is often regulated through a feedback mechanism where the ...

Amyloid Fibrils

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Cooperative Allosteric Transitions

Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand ...

Antibody Structure

Phosphorylation

Ligand Binding Sites

Proteins are dynamic macromolecules that carry out a wide variety of essential processes; however, the activities of most proteins depend on their ...

Protein Kinases and Phosphatases

Proteins undergo chemical modifications that trigger changes in the charge, structure, and conformation of the proteins. Phosphorylation, acetylation, ...

Protein-protein Interfaces

Many proteins form complexes to carry out their functions, making protein-protein interactions (PPIs) essential for an organism&#39;s survival. Most PPIs ...

GTPases and their Regulation

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Conserved Binding Sites

Many proteins&#8217; biological role depends on their interactions with their ligands, small molecules that bind to specific locations on the protein ...

Covalently Linked Protein Regulators

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The Equilibrium Binding Constant and Binding Strength

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Integrate evidence to develop a structural model of a DNA molecule. Using the model, develop and communicate an explanation for how DNA serves as a template for self-replication and encodes biological information.
EXPLANATION: Discussions of DNA in earlier grades have been limited to discussions of genes and the role of genes in the appearance and activities of an organism. Biology 1 represents a student's introduction to a molecular model of a DNA as well as the organization of DNA into genes and genes subsequently into chromosomes. Students should address interactions between genes in proteins which regulate both the shape and reproduction of DNA molecules. It is important to note that not all segments of DNA are transcribed for proteins. Portions of DNA are involved in regulating the expression of genes or affect the structure of the chromosomes (replication origin, centromeres, and telomeres).

How Allosteric Control Changes Enzymes

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